Extended support for in-line chained lambdas

[SougandhS]

This pr enables users to select a lambda in a single-line chained lambda expressions to put a lambda entry breakpoint + updated chained lambda breakpoint names in breakpoints view

Fixes : #732

On toggling lambda entry breakpoint on chained lambda exps

Debugger will show an UI to select the indented lambda of user's choice

User can select the lambda inside the small popup either by double click or click->select via button,

On selecting, breakpoint will be added specific to that lambda

LambdaNew.mp4

What it does

How to test

Author checklist

• I have thoroughly tested my changes
• The change is following the coding conventions
• I have signed the Eclipse Contributor Agreement (ECA)

[SougandhS]

@iloveeclipse - Could you please review when you get time ?

[SougandhS]

random Test failure -> #719

[SougandhS]

@iloveeclipse I have resolved the merge conflicts 👍

[iloveeclipse]

Few impressions after a quick black box test, without looking into the code.
In general, the idea is useful, but implementation has at least one major bug and also UI needs to be polished.

Take the file below and try that below:

import java.util.Arrays;
import java.util.List;
import java.util.Optional;

public class BreakpointsTest {
	
	public static void main(String[] args) {
		callMe();
	}

	private static void callMe() { 
		BreakpointsTest t = new BreakpointsTest();
		t.lotOfLambdas();
	}
	
	void lotOfLambdas() {
		Optional.of("aa").map(this::a6).filter(x -> x.isBlank()).map(this::a6);

		List<String> list = Arrays.asList("a", "b", "c");
		list.stream().filter(s -> s.length() > 0).map(s -> s.toLowerCase()).filter(x -> x.charAt(0) > 1).map(s -> s.toUpperCase()).filter(k -> k.indexOf(0) < 0).map(s -> s.toLowerCase()).filter(p -> !p.isBlank()).forEach(System.out::println);
		
		list.stream().filter(s -> s.length() > 0).map(s -> s.toLowerCase()).filter(x -> x.charAt(0) > 1).map(s -> s.toUpperCase())
				.filter(k -> k.indexOf(0) < 0).map(s -> s.toLowerCase()).filter(p -> !p.isBlank()).forEach(System.out::println);
		
		list.stream().filter(s -> s.length() > 0).map(s -> s.toLowerCase()).filter(x -> x.charAt(0) > 1)
				.map(s -> s.toUpperCase()).filter(k -> {
					System.out.println(k);
					return k.indexOf(0) < 0;
				}).map(s -> s.toLowerCase()).filter(p -> !p.isBlank()).forEach(t -> {
					if(t.contains("a")) {
						System.out.println(t + "!!!");
					}
				});
	}
	
	String a6(String s) {
		return s;
	}
}

1. Major bug: "Toggle Breakpoint" works to create breakpoints but is broken for deleting breakpoints, breakpoints can't be removed from editor anymore (only via Breakpoints view). It seem breakpoints can be "toggled" only on lines where lambda breakpoints can be created via "Toggle Lambda Breakpoint" menu.
2. Bug: if one closes lambda proposal dialog by "cancel", no breakpoint is created but on next double click on same line no lambda proposals dialog is shown and a regular breakpoint is created. Expectation is: on "Cancel" nothing is created and no behavior is changed. After playing with that for some time I was not able to show up lambda selection dialog anymore, independently what I've tried - without any error in the log.
3. UI problem: the shown list of lambda's is resizable but the content inside is fixed.
4. UI problem: extra line added for block expressions:
   

[SougandhS]

Few impressions after a quick black box test, without looking into the code. In general, the idea is useful, but implementation has at least one major bug and also UI needs to be polished.

Thanks for testing, will fix and get back 👍

[SougandhS]

1. Major bug:

Fixed

2. no breakpoint is created but on next double click on same line no lambda proposals dialog is shown

Lambda proposal is only shown when user do Right click->Toggle lambda Entry breakpoint . Double click creates Line breakpoint only

After playing with that for some time I was not able to show up lambda selection dialog

Strange. I tried many times and it was working for me, can you try again ? or share the exact same step you tried

3 the shown list of lambda's is resizable but the content inside is fixed.

Fixed

4 extra line added for block expressions:

Handled

[SougandhS]

@iloveeclipse could you please check this again ?

[SougandhS]

Hi @iloveeclipse
Could you please re-review this once you are available ?

[eclipse-jdt-bot]

This pull request changes some projects for the first time in this development cycle.
Therefore the following files need a version increment:

org.eclipse.jdt.debug.ui/META-INF/MANIFEST.MF
org.eclipse.jdt.debug.ui/pom.xml
org.eclipse.jdt.debug/META-INF/MANIFEST.MF

An additional commit containing all the necessary changes was pushed to the top of this PR's branch. To obtain these changes (for example if you want to push more changes) either fetch from your fork or apply the git patch.

Git patch

From 4368217a4c474a78286515275a4d78f16ca93887 Mon Sep 17 00:00:00 2001
From: Eclipse JDT Bot <[email protected]>
Date: Mon, 8 Sep 2025 06:02:35 +0000
Subject: [PATCH] Version bump(s) for 4.38 stream


diff --git a/org.eclipse.jdt.debug.ui/META-INF/MANIFEST.MF b/org.eclipse.jdt.debug.ui/META-INF/MANIFEST.MF
index a4f478043..58c8e615c 100644
--- a/org.eclipse.jdt.debug.ui/META-INF/MANIFEST.MF
+++ b/org.eclipse.jdt.debug.ui/META-INF/MANIFEST.MF
@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %pluginName
 Bundle-SymbolicName: org.eclipse.jdt.debug.ui; singleton:=true
-Bundle-Version: 3.15.100.qualifier
+Bundle-Version: 3.15.200.qualifier
 Bundle-Activator: org.eclipse.jdt.internal.debug.ui.JDIDebugUIPlugin
 Bundle-Vendor: %providerName
 Bundle-Localization: plugin
diff --git a/org.eclipse.jdt.debug.ui/pom.xml b/org.eclipse.jdt.debug.ui/pom.xml
index 212983904..dcfe6c67b 100644
--- a/org.eclipse.jdt.debug.ui/pom.xml
+++ b/org.eclipse.jdt.debug.ui/pom.xml
@@ -18,7 +18,7 @@
   </parent>
   <groupId>org.eclipse.jdt</groupId>
   <artifactId>org.eclipse.jdt.debug.ui</artifactId>
-  <version>3.15.100-SNAPSHOT</version>
+  <version>3.15.200-SNAPSHOT</version>
   <packaging>eclipse-plugin</packaging>
   <properties>
   	<defaultSigning-excludeInnerJars>true</defaultSigning-excludeInnerJars>
diff --git a/org.eclipse.jdt.debug/META-INF/MANIFEST.MF b/org.eclipse.jdt.debug/META-INF/MANIFEST.MF
index 1a6f573b1..39dc0010b 100644
--- a/org.eclipse.jdt.debug/META-INF/MANIFEST.MF
+++ b/org.eclipse.jdt.debug/META-INF/MANIFEST.MF
@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %pluginName
 Bundle-SymbolicName: org.eclipse.jdt.debug; singleton:=true
-Bundle-Version: 3.24.0.qualifier
+Bundle-Version: 3.24.100.qualifier
 Bundle-ClassPath: jdimodel.jar
 Bundle-Activator: org.eclipse.jdt.internal.debug.core.JDIDebugPlugin
 Bundle-Vendor: %providerName
-- 
2.51.0

Further information are available in Common Build Issues - Missing version increments.

[SougandhS]

Hi @iloveeclipse
I’ve made some code optimizations and fixed a few UI issues. Could we plan this for M2 or M3?

[iloveeclipse]

I hope to find time tomorrow

[SougandhS]

What I see is just a dialog that appears somewhere on the screen, independently where I have my cursor. It seem trying to open it time to time on different places, but never places it in a way that one could clearly "link" the dialog to the lambda selected.

I believe once this sync feature is added one could clearly link with selection because the popup will always open few distance below the actual code

[iloveeclipse]

I believe once this sync feature is added one could clearly link with selection because the popup will always open few distance below the actual code

I've slightly modified the dialog from my patch. Now user can select something in editor. I would prefer to use this dialog, all what is needed now is to set dialog selection on cursor changes, which you seem to done already in private patch. If you could apply this patch to the dialog, we could be all happy I assume.

[SougandhS]

I've slightly modified the dialog from my patch. Now user can select something in editor. I would prefer to use this dialog, all what is needed now is to set dialog selection on cursor changes, which you seem to done already in private patch. If you could apply this patch to the dialog, we could be all happy I assume.

Thanks, I have added the sync selection

My.Movie.mp4

[SougandhS]

This is not correct. My patch keeps lambda positions as they are written. I guess you had troubles to compile the patch properly.

there's something wrong with the comparator

list.stream().map(s -> s.toLowerCase()).filter(s -> s.length() > 0).map(s -> s.toLowerCase()).filter(x -> x.charAt(0) > 1)

positions of 2nd and 3rd are interchanged..

Edit : The comparator fails when there are duplicate entries.

[SougandhS]

I have fixed with the comparator issue when there are duplicate entries

[SougandhS]

If there are no more changes can this be merged ?

[iloveeclipse]

I will now fix remaining items, squash everyting and update the PR.

[SougandhS]

I will not fix remaining items, squash everyting and update the PR.

PR updated 👍

[iloveeclipse]

I did final pass through the changes, see comments.

I will fix all code comments in a dedicated commit to show the differences and then squash all together once again.

[iloveeclipse]

@SougandhS : thanks for the feature. Please provide N&N entry.

PS:
if you have time, would be great have the preference page entry for #798

[SougandhS]

Thank you for the cleanup and improvements

if you have time, would be great have the preference page entry for #798

Looks like the original author has already implemented it via #81